Police said Islam was killed by assailants on two motorcycles when he left the shop that he owned with his father in Hyderabad city in southern Sindh province.

"He sustained four bullets in his head and abdomen and died on the spot," Akhtar Hussain, a police official, told AFP news agency.

His father was not injured, but police said he was in "deep shock".

Islam was running for the Sindh provincial assembly in national and regional elections on May 11.

Second politician killed

The polls will mark the first democratic transition in Pakistan, which has been subject to extended periods of military rule.

Islam's death was the second such killing during Pakistan's election campaign. Adnan Qualti, a Pakistan People's Party candidate, was killed on April 2.

Pakistan's umbrella Taliban faction has directly threatened the main secular coalition partners in the outgoing government.

Aamir Latif, Karachi bureau chief of Online News Network, told Al Jazeera the Tehreek-i-Taliban, or the Pakistani Taliban, was turning its attention away from official military targets and was now targeting civilians in the run-up to the election.

The MQM said Islam had been targeted deliberately and accused "terrorists" of trying to sabotage a peaceful democratic process.

"The way he has been killed and his father remained unhurt shows the precision the killers have and also their intention to target him in particular," Wasay Jalil, MQM spokesman, said.

"Terrorists are threatening to sabotage elections ... but these terror acts will not deter us from taking part in elections and our stance against extremism and terrorism."

Deeply troubled cities

Hyderabad is the second largest city in Sindh after the port city of Karachi, which is deeply troubled by ethnic and political killings.

Latif told Al Jazeera the Pakistani Taliban had targeted candidates in the Karachi area and the northwest of the country to prove its presence in the region and show it had the power to disrupt the election campaign.

"They want to dispel any impression that they have gone weak in the wake of, and loss of, public sympathies and successful military operations in some of the tribal areas, which were earlier considered to be the strongholds of Taliban," he said.

Latif said that it would force the parties to run low-profile campaigns, but the Taliban's objective would fail because voters in Pakistan traditionally stayed loyal to their parties.

"Such kinds of tactics do not, will not, go in favour of the right-wing parties," he said.